Automatic load-regulator for piston-compressors



March 31, 1936- A. HOERBIGER El AL AUTOMATIC LOAD REGULATOR FOR PISTON COMPRESSORS Filed March '7, 1952 Patented Mar. 31, 1936 UNITED STATES PATENT OFFICE AUTOMATIC LOAD-REGULATOR FOR PISTON-COMPRESSORS Application March 7, 1932, Serial No. 597,396 In Austria March 11, 1931 2 Claims.

We have filed applications in Austria on Mar. 11, 1931 and June 3, 1931, Germany June 26, 1931 and Czechoslovakia July 7, 1931.

This invention relates to an improved automatic load regulator for piston compressors. Load regulators for piston compressors are already known which effect a regulation of the load or output by holding the inlet valves open throughout the Whole or part of the compression stroke. This result has been obtained in practice by mechanical, hydraulic, pneumatic, or electro-magnetic means, generally through a switching device with oblique controlling or operating surfaces and in association with a compressed air regulator.

The present invention relates to load regulators of the type in which the inlet valves are opened electro-magnetically during a portion of the compression stroke corresponding to the load, by means of a switching device which can be operated both by hand and by a compressed air regulator.

With the known type of construction of the regulator according to the present invention the switching in and out of the coils results in current fluctuations which, in the case of multistage compressors have a disturbing influence in view of the larger number of coils. These coils are constantly traversed by the current in the same direction, so that the increasing residual magnetism of the magnets renders prolonged control impossible, and makes it necessary to replace periodically the armature which actuates the inlet valves.

In order to obviate these drawbacks there are associated with each inlet valve in accordance with the invention four coils which are arranged to be traversed by the current in pairs in opposite directions, so that during the regulating action two coils always co-operate in such a manner that the iron core is at times subject to an alternating magnetic flux and at times demagnetized, and at the same time the remaining two coils are dead. In this manner a perpetual polereversing of the magnets is effected which prevents the occurrence of residual magnetism and enables prolonged controlling of the valves to be achieved. Since there is always the same large number of magnets connected to the source of current, current fluctuations are effectually and entirely obviated.

Fig. 1 is a view partly in elevation and partly in section and showing a portion of the invention as used in connection with a suction valve.

Fig. 2 is a diagrammatic arrangement of the switching mechanism used herewith.

Fig. 3 is a detail section taken vertically through the axis of the rotating member used herein and shown in the upper part of Fig. 2.

A horseshoe-shaped iron core 30 (Fig. 1) is provided on one of its limbs with four coils 3|, 32, 33 and 34 which are so wound and traversed by current that the coils 3|, 32 magnetize this limb for instance as south pole, and the coils 33, 34 as north pole. An armature in the form of a lever 36 pivoted at is articulated to a rod 38 connected to catch links 31. A spring 39 normally retains the valve plate 40 in the closed position. The coils are so controlled during the compression stroke by means of an arrangement to be described in due course that at one time during the operation a pair of these coils are connected to the source of current. If the pairs of coils 3|, 32 or 33, 34, respectively, be connected to the current supply the lever 36 will be attracted and the valve opened. But, if either the pair of coils 3| and 33 or the pair 32 and 34 are connected in the circuit, the lever 26 remains uninfiuenced since under these conditions the coils in circuit neutralize each other in their electromagnetic eifects.

The coils are connected on the one hand to a source of current 4| (Fig. 2) and on the other hand to the sliding contacts 42, 43, arranged upon the carrier or disk 46 and to the sliding contacts 44, (Fig. 2) arranged upon a spider 48, said sliding contacts 42, 43, 44, 45 being associated with a disk 46 having a semi-circular contact surface 4! and said disk being fixed upon a shaft 5| carrying the spider 48. The disk 46 is driven by means of a suitable gearing from a shaft of the compressor in dependence upon the drive of the compressor in such manner that for every two revolutions of the compressor only one revolution is performed by the disk. The contacts 42, 43, connected to the coils 3| and 34 (Fig. 2) are fixedly arranged, while the contacts 44, 45, are arranged on the spider 48 which is rotatable on the shaft 5| by means of a gear 49 and rack 50. The rack 53 is adjustably moved as by connection to a governor of the compressor or by manual means. Figure 2 also shows the electrical wiring for the control of two valves for stepwise and alternative operation, in which case the arrangement of Fig. 1 would be doubled. Coordinated to the second valve are the coils 3| a to 34 (Fig 2) which are connected to the source of current in the same manner by means of fixed contacts 42 43 and movable contacts 44 45 The contacts 42 43 take up positions between the contacts 42, 43, While the contacts 44 45 are arranged upon the spider 48.

Since the mode of operation of the arrange- 5 ment for controlling both inlet valves is the same for each magnet, for the sake of simplicity merely the controlling of the coils 3| to 34 will be described. When the movable contacts 44, 45 are opposite the fixed contacts 42, 43, the coils 31, 32 and 33, 34, respectively, will be alternately connected to the source of current on thepassing'df the contact surface 41, thus alternatingly reversing the magnetization of the limb of the iron core 30. The lever 36 is attracted and retained by the magnet core, so that the valve remains permanently open and the compressor runs idle. If the spider 48 be turned in an anti-clockwise direction into the position shown, the contact surface 41, which revolves in a clockwise direction, '20 after leaving the contact 43 connects the coils "3|, '32 to the source of current until such time as this contact surface comes clear of the contact 44, "whereupon the contact45 is-connected inand in place ofthe'coil '32 and the 001133 is traversed by thecurr'ent. The coils 3L33 cancel each others magnetic effect, the valve plate is closed under the action of the spring 39, and the lever 36 is thereby rocked away from the magnet core. When the contact surface comes clear of the contact '42, the

contacts 45, '43 'are'connected to the source of "current, the lever 3'6 is'attractedby the coils 33, "34 acting as north 'pole, and the valve is held open until the contact surface comes clear of the contact '45 whereupon the coil 32 is connected up,

35 the magnetic effect of the coils 32 and 34 ceases and the valve is closed. After the contact surface'4'l has left its contact the cycle starts afresh. 'Ihemore the spider isrotated the longer the coils are connected vvith' opposed magnetic eflect, 4 and the longer the valve is kept closed. The compressorappr'oaches nearer and-nearer to full load which isattaine'd when the contacts 4-3, 44 and '42, 45, respectively, come opposite each other. In this casethere are always'two coils of diiferent 4 denomination connected up so that their action is canceled.

ingtwo in the opposite direction, an armature for said magnet operatively connected to said valve to open the same upon energization of the magnet, a source of current and a rotary contact device adapted to be driven from the rotating member of a compressor and successively connecting the source of current with a pair of coils wound in one direction, a pair of coils selected from the two sets of coils each wound in an opposite direction, and the pair of coils wound in the opposite direction -to the first pair.

2. An automatic load regulator for a piston compressor having a suction valve and a rotating member, saidload regulator including an electromagnet having a core carryingfour coils, two-of which are wound in one direction and the remaining two in the opposite direction, anarmature for said-magnet operatively connected to said valve to open the same upon energization'of the-magnet, 'asourceof current andarotary contact device adapted to be driven from the rotating member of a compressor and successively connecting the source of current 'with'a pair 'of coils wound in one direction, a pair of coils selected'from the two sets of coils each wound in an opposite direction, and the pair of coils Wound in the opposite direction to the first pair, said contact device including a shiftable member rotatably mounted to vary the times of energization of said coils.

ALFRED HOERBIGER.

EMIL SCHRQAMM. 

